Method of detinning tin-scrap.



M. LEITCH. METHOD or DETINNINQTIN SCRAP.

APPLIOATIONIILED SEPT. 19, 1908.

Patented Dec. 15, 190,8.

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UNITED sTATns PATENT orricn.

MEREDITH LEITFH, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOR- TO METL PROCESS COMPANY, OF NEW YOli-Kv, N. Y., A CORFORATION OF NEW YORK.

METHOD OF DETINNIG TIN-SCRAP.

Patented Dec. 15, 1908.

Original application filed February 28, 1907, Serial No. 359,854. Divided and. this application led September 19. 1908. Serial No. 453,876.

To all-whom it may' concern.' l

Be 1t known that I, MEREDITH LEITCH, a citizen of the United States, residing4 at Springfield, Hampden county, Massachu setts, have invented certain new' and useful Improvements in Methods of Detinniug Tine Scrap, of which the following is a full, clear, und exact description.

8 is a return pi )e leading from beneath the surface of the e ectrolyte and the heatlng tank 7 and discharged beneath the sin-tace of the electrolyte and within the detinniu tank 5. The electrolyte which I prefer to use is caustic soda. The electrolyte is caused to :l circulate by a )ump 9 situated in .the pipe My invention relates to iniprm'enicnts in the methods of dctinning tin scrap by apparatus employing a circulating elcctrolytfe, such for insta ice as caustic soda. and has 'for its object to reduce the deterioration of the electrolyte. carbonio acid in the airunites with elements in the caustic soda, causing it tc carbonate and vconsequtmtly deteriorate. vl have observed that when the electrolyte is circulated in the ordinary way, waterfalls are produced and air is entraine-d during the circulation, so that a large amount ot air 1s thus I brought into contact with the electrolyte and the carbonating und consequent deterioration takes place rapidly.

In carrying out my invention l prevent the entraining of air preferably at any and all points. I also draw the liquid oli and intro- 4 duce it at the most desirable points and heat it so as to maintain it at the proper degree of tem erature. v Y

T e following is a description ofniy invention and of apparatus suitable for carrying it out, reference being had to the accompanyin drawings, which show the apparatus in sit o elevation with parts broken away.

'Referring more particularly to the drawings, 1 is av asket'containing the tin scrap to be detinned and having a suitable conveyer therein to cause the scrap to pass through the detinning bath.

2 are cathode plates upon which the tin re- `moved from the scrap is deposited.

3 and 4 are circuit terminals connected to the basket vand the cathode lates respectively and supplied with electricity from any suitable source.

v l'5 is a tank containingthe electrolyte in which the scrap andthe cathode plates are immersed.

6 is an outlet pi e leading to a heating tank 7 and so arran e as to draw the electrol .te from near the ottom'of the tank 5 and ischarge it in proximity to the bottom of the heating tank 7.

'Yhencaustic soda is used, the

leading from t e'bottoni of the detinning tank 'to the bottom of the heating tank. By

Q tht` arrangement thus described, the electrolyte is circulated from the detinning tank to the heating tank and back without the presence of any waterfall, and thereby the entrainnient of all air is prevented and the only portions of the electrolyte which are exposed to the air so as to be affected by it being the surfaces of the two tanks. The electrolyte by the heating tank 7 is kept at the desired temperature.

By reason of my improvement the iref quency of regenerating the electrolyte is very much reduced since its deterioration is very largely prevented, it being necessary to draw ofi only a portion of the electrolyte from time to time in order to prevent it from bccoming fatigued by reason of the carbonating that necessarily takes place.

When the pump is in operation, the eii'ert is to draw the electrolyte from thev detinning bath near the bottom where it is coolest, and

lforce it into the heating boiler to a height above the level inthe bath so that it flows out into the bath by its 'own h ad. l1 leaves the heating boiler without entra-innig air as the-mouth of the return pipe is below the surface therein, and delivers the liquid into the bath below the surface so as not' to drive in any air at that point. The electrolyte with this arrangement becomes carbonated much more slowly than is the case in systems where the circulation takes place with one or more waterfalls, and materially reduces the labor and expense otherwise necessary to keep it in proper condition.v

This application is a division ofiny pending lapplication Serial No. 359,854-, filed Februa-ry 28, 1907.

1. Inl the method of operating detinning apparatus employing a circulating electrolyte, like Acaustic soda, the improvement which consists in drawing the electrol vtcput of the detinning bath fr ombeneaht e 'sre face of the electrolytetherein .anc returning it to said bath at a point below said surface heat.

' the level of the .eleetolytc therein.

and subjecting 'portions so Withdrawn to 2.111 the method of operating detinning apparatus employing a circulating `electrolyte, like caustic soda, the'improvement whichA 3. In the method fof operating detinnng apparatus employing a circulating electrolyte, like caustic soda, the improvement which consists in causing the electrolyte to pass through a series of tanks, one of which is the det ing bath and another of Whichis a heatin bath, heating the said electrolyte in sai heating bath and-causing it to both enter and'leave each of said tanks at points below the level of the electrolyte therein, eausinsaid .electrolyte to enter the detinning bath eloviT but in proximity to the 'surface of the liquid therein and to leave said bath at apoint in proximity to its bottom and to enter said heating bath at a point in proximity to its bottom and leave the same at a point beloW but in proximity to the sur- 30 face of the liquid therein.

MEREDITH LElTCH.

l Witnesses: l

FREDERICK K. EEARNSIDE. JOHN J. DoNELAN. 

